<?php

/**
 * CGettextPoFile class file.
 *
 * @author Qiang Xue <qiang.xue@gmail.com>
 * @link http://www.yiiframework.com/
 * @copyright Copyright &copy; 2008-2011 Yii Software LLC
 * @license http://www.yiiframework.com/license/
 */

/**
 * CGettextPoFile represents a PO Gettext message file.
 *
 * @author Qiang Xue <qiang.xue@gmail.com>
 * @package system.i18n.gettext
 * @since 1.0
 */
class CGettextPoFile extends CGettextFile {

    /**
     * Loads messages from a PO file.
     * @param string $file file path
     * @param string $context message context
     * @return array message translations (source message => translated message)
     */
    public function load($file, $context) {
        $pattern = '/(msgctxt\s+"(.*?(?<!\\\\))")?'
                . '\s+msgid\s+"(.*?(?<!\\\\))"'
                . '\s+msgstr\s+"(.*?(?<!\\\\))"/';
        $content = file_get_contents($file);
        $n = preg_match_all($pattern, $content, $matches);
        $messages = array();
        for ($i = 0; $i < $n; ++$i) {
            if ($matches[2][$i] === $context) {
                $id = $this->decode($matches[3][$i]);
                $message = $this->decode($matches[4][$i]);
                $messages[$id] = $message;
            }
        }
        return $messages;
    }

    /**
     * Saves messages to a PO file.
     * @param string $file file path
     * @param array $messages message translations (message id => translated message).
     * Note if the message has a context, the message id must be prefixed with
     * the context with chr(4) as the separator.
     */
    public function save($file, $messages) {
        $content = '';
        foreach ($messages as $id => $message) {
            if (($pos = strpos($id, chr(4))) !== false) {
                $content.='msgctxt "' . substr($id, 0, $pos) . "\"\n";
                $id = substr($id, $pos + 1);
            }
            $content.='msgid "' . $this->encode($id) . "\"\n";
            $content.='msgstr "' . $this->encode($message) . "\"\n\n";
        }
        file_put_contents($file, $content);
    }

    /**
     * Encodes special characters in a message.
     * @param string $string message to be encoded
     * @return string the encoded message
     */
    protected function encode($string) {
        return str_replace(array('"', "\n", "\t", "\r"), array('\\"', "\\n", '\\t', '\\r'), $string);
    }

    /**
     * Decodes special characters in a message.
     * @param string $string message to be decoded
     * @return string the decoded message
     */
    protected function decode($string) {
        return str_replace(array('\\"', "\\n", '\\t', '\\r'), array('"', "\n", "\t", "\r"), $string);
    }

}
